> Are you describing Erich von Däniken's inability to change his mind when evidence clearly contradicted his theories?

He wasn't that unwavering. About the iron pillar of Delhi he said in his first book that it doesn't rust and thought this being a proof for alien interference. Later he turned around and said "By now this damn thing is rusting!".

But he never changed his opinion on his basic premise. I guess it's easy to not change your theory if it can't actually be disproved. There are so many unknowns and gaps in history that you have enough space to fit a few ancient aliens in there.